A number of systems have been developed for evacuating accumulations of blockages in wellbores to include oil and gas producing wells. The blockages may include accumulations of sediments and other solids generated from the well. A well is typically lined at the upper portion with a casing, and the down-hole portion is lined with metallic, plastic, or other liners, sometimes referred to as “well tubulars”. The tubulars may be in the form of production tubing, and slotted or wire-wrapped liners. The well tubulars may be particularly susceptible to corrosion, and deposits may develop on the tubulars such as silicates, sulfates, sulfides, carbonates, calcium and organic growth.
One solution for performing well cleaning operations is to utilize a cleaning implement placed down-hole that also carries a cleaning solution. The cleaning implement forms the distal end of a tubular member placed down-hole, referred to as coiled tubing. The coiled tubing is placed into the well to perform the cleaning operation to include the injection of treating and cleaning fluids, which remove blockages and otherwise clean the well tubulars. The circulation and cleaning fluid may include water, acid, foam, chemical cleaning solutions, and corrosion inhibitors.
It is desirable to perform an efficient well cleaning operation in which the coiled tubing is advanced into the well as quickly as possible, and then the fluid is injected into the well. The cleaning implement in conjunction with the cleaning fluid provides both mechanical and fluid/chemical cleaning which under most circumstances adequately cleans the wellbore.
Depending upon the depth and number of wells to be cleaned, a significant amount of cleaning fluids may be required to adequately clean the targeted wells. Because of environmental concerns in most locations, the cleaning fluids cannot be disposed of by allowing the fluid to be dumped onto the surrounding land. Therefore, there is an operational requirement to prevent the cleaning fluids from contacting the ground. Significant measures are taken to retrieve the used cleaning fluids in order to dispose of the fluids in an environmentally responsible manner.
One system disclosed for cleaning a well is found in U.S. Pat. No. 4,919,204. This reference more specifically discloses a cleaning apparatus for pressurized cleaning of well flow conductors. The apparatus provides cleaning of the conductors by use of the apparatus in combination with high pressure directed fluid jets that flow through the apparatus. Rotation of the cleaning apparatus can also be used for combined mechanical and hydraulic drilling to remove deposits from within the well flow conductors. The reference discloses coiled tubing mounted on a reel, and the reel itself is mounted on a vehicle. A manifold is connected to the coiled tubing. The manifold includes the necessary pumps, valves, and fluid reservoirs to discharge high pressure cleaning fluid through the coiled tubing into the wellbore.
Another example of a system for cleaning a well is disclosed in the U.S. Pat. No. 7,549,468. Specifically, the reference discloses a coiled tubing injector system which includes transport trailer components for separate transfer to and from a drilling site. Each component is taken to the site with its own transport tractor, a first component including a coil storage reel and a second component including a tubing injector carried on a mast which is raised from a horizontal transport position, through a stabbing and unstabbing position to a raised working position. When the components are arranged together in an end-to-end with the mast in a stabbing position, a tube gripping member is positioned between the storage reel and tubing injector for controlling the handling of a free end of the stored tubing for stabbing and unstabbing of the tubing injector
Other examples of wellbore cleaning devices include the U.S. Pat. Nos. 4,744,420 and 7,377,283.
As environmental regulations become more stringent, particularly in areas such as the Arctic, extreme measures have to be taken to prevent the inadvertent spillage of any cleaning fluid. The cleaning fluid cannot be permanently stored and treated at the well location and, therefore, once the cleaning fluid is spent, the cleaning fluid must be trucked offsite to a treatment facility. Often times, the treatment facility is many hundreds of miles from the well locations. Thus, one significant problem with well cleaning operations is the time and expense involved with trucking the needed cleaning fluid to and from the well locations.
Therefore, there is a need to provide a well cleaning system in which the logistics associated with use of the cleaning fluid are simplified and made more efficient. Furthermore, there is also a need to greatly conserve the use of the cleaning fluid, not only for purposes of addressing the logistical concerns, but also to reduce the risk that a significant amount of cleaning fluid could be inadvertently spilled.
There is also a need to provide an integrated cleaning solution in which the system can be easily transported to remote locations where vehicle access is limited to off-road type vehicles or vehicles that otherwise can travel on unimproved roads.
There is also a need to provide a cleaning solution that is self contained and automated which reduces manpower requirements and allows remote control of the system which may be installed at remote geographical locations.